Mercury switch relay



Feb. 25, 1941. c, H, LARsoN MERCURY SWITCH RELAY Filed May 22, 1959 A/A/E Feb. 25, 1941.

C. H. LARSON MERCURY SWITCH RELAY Filed May 22, 1939 @MA/@M Patented Feb. 25, 1941 PATENT OFFICE MERCURY SWITCH RELAY can u. Larson, Elkhart, ma., assigner terne Adlake Company, a corporation o! Illinois application May 2z, 1939, serial No. 275,099

20 Claims.

This invention relates to mercury switch relays and in order to understand the objects of the invention, it is necessary to define certain terms that will be used:

Normal operate time is the time required to produce a change inthe electrical circuit through the switch when the relay winding is suddenly closed while all parts of the switch are lying in stable equilibrium.

Normal release time is the time required to produce a change in the electrical circuit through the switch when the relay winding is suddenly opened while all parts of the switch are lying in stable equilibrium.

Normal operate recycling time is the minimum period during which the relay winding must be permitted to remain open in order that the normal operate time is obtainable when the relay winding is suddenly closed. Usually, though not always, the normal operate recycling time is the same as the time required for the switch elements to reach stable equilibrium after the relay winding has been opened.

Normal release recycling time is the minimum period during which the relay winding must be permitted to remain closed in order that the normal release time is obtainable when the relay winding is suddenly opened. Usually, though not always, the normal release recycling time is the same as the time required for the switch elements to reach stable equilibrium after the relay winding has been closed.

Quick operate reset refers to the ability of a. switch to give normal operate time without requiring a particular time interval to precede the closing of the r'elay winding.

Quick release reset refers 4to the ability of a switch to give normal release time without requiring a particular time interval to precede the opening of the relay winding.

Obviously in writing commercial specifications for relays of this kind, minimum and maximum values are often given for operate and release time, these values representing time intervals which must be met regardless of the relative positioning of the switch parts (i. e. in stable equilibrium or not) at the instant that the condition of the electrical circuit through the relay winding is changed. The minimum values are usually specified to prevent an immediate change in circuit condition in the event of subnormal recycling conditions, and the maximum (Cl. 20o-97) fications calling for unusual operating characteristics.

Further objects and advantages will become apparent as the disclosure proceeds and the description is read in conjunction with 'the accompanying drawings, in which Fig. 1 is a vertical, sectional view showing a front contact switch embodying the principles of this invention;

Fig. 2 is a view showing the manner in which the mercury cup is always filled whenever the displacer rises;

Fig. 3 is a view showing the switch parts in equilibrium when the relay coil has been energized a suiliclent length of time;

Fig. 4 shows a back contact relay constructed in accordance withA the teachings of this invention, the switch parts being shown in their position of equilibrium when the relay coil is cie-energized; and

Fig. 5 is a view of the back contact relay of Fig. 4 showing the switch parts in the position which they assume when in stable equilibrium and the relay coil is energized.

The embodiments of the inventions shown in the drawings and hereinafter described have been chosen for specific illustration and description in compliance with Section 4888 of the Revised Statutes, but the appended claims should not be limited by the specific constructional details of the relays unless required by the prior art.

Front contact switch (Figs. 1-3) The relay shown in Figs. 1 3 inclusive is designed to have the following operating characteristics: Normally open contact (i. e. a front contact switch); minimum operate time; and quick release reset.

The manner in which these operating characteristics are obtained may be understood by referring first to Figs. 1-3 inclusive which show a front contact relay comprising a coil I having poles II and I2 which receive a time delay mercury switch generally designated I3.

The switch comprises an envelope I4, preferably of low expansion boro-silicate glass through the base of which leads I and I6, preferably of molybdenum or tungsten, are pinch-sealed, the

leads projecting upwardly through the mercury fill l1 and having insulating sleeves I8. The sleeve associated with the lead I6 is broken away, as at 9, so that the lead is always in contact with the mercury fill I1. The sleeves are fused together as indicated at I9 to form a seat for a mercury leakage time delay cup, generally designated 20, which consists of a tubular piece 2l of ceramic material, preferably Alundum, which is fused or otherwise bonded to the seat Il to form a mercury reservoir 22. Preferably thecup2lisbeveledasindicatedat22.sothat mercury can readily enter the reservoir 22 on the right side (Pig. 1) of the cup while gas within the cup escapes along the left side of the cup. In this way. there is no opportunity for the mercury cup 2l to be incompletely iilled by reason of gas bubbles becoming trapped within the cup.

The lead Il projects upwardly into the cup 22 and is insulated from the mercury within the cup by a glass sleeve 2l which is enlarged at its upper end to form a seat 2l for a smaller cup 26 of ceramic material adapted to contain a small pool of mercury 21 constantly in contact with the exposed electrode portion 2l of the lead Il. 'Die lead Il has its upper end 20 exposed to the mercury in the time delay cup 22.

The cup 22 is provided with a restricted side opening 8l which is at all times below the mercury level when functioning as a time delay element. Its sise is dependent upon the desired operating characteristics of the switch and it controls the i'iow of mercury from the cup 22 when the circuit between the electrodes 2l and 2l is being broken.

A plunger or displacer, generally designated 3|, is provided to manipulate the mercury illl in response to the relay coil Il. It comprises an iron sleeve 22 within which is telescopically mounted a glass thimble Il closed at its upper end by a porous wall Il that is also preferably formed of ceramic material. such as Alundum. The thimble 22 is held in xed relation to the iron sleeve 22 by means of upper and lower 'cushioning springs I! and 2l that are telescoped over the projecting ends of the thimble and clamp guide washers 21 and 2l between the springs and the ends of the sleeves 32. The guide washers have peripheral cut-out portions, not shown. which permit mercury to flow past the washers between the plunger and the envelope wall.

Before the switch envelope is sealed oil at 39, a suitable gas illl is inserted in the envelope, and experience has shown that helium. hydrogen. or a mixture of the two elements constitute a satisfactory gas lill.

For the relay to operate in its intended manner.atleastinsofarasithastomeetthe conditions hereinbefore set forth, it is necessary for the time delay element 3l in the displacer to be relatively fast in its eilective action as compared with the mercury leakage opening 2l in the time delay cup 2l. For example, if the relay is to have a minimum operate time of one second and a minimum release time of live seconda, the time delay element Il may be chosen so that it has a normal operate time of one second, and the hole 3l may he made of such size that ve seconds ls required for suflicient mercury to flow from the cup 22 to lower the mercury level within the cup from its maximum level adjacent to the lowest margin of the beveled opening to a level in which the mercury 2`| within the cup 28 separates with the mercury in the cup 22.

The thimble 23 constituting part of the displacer 2|, has a side opening Il which permits gas to enter the, thimble I2 whenever it is above the level of mercury on the outside of the disF placer Il (for convenience called the outside mercury level) thereby by-passing or rendering ineffective the time delay element 2|.

Operation of front contact switch When the relay coil il is energized at a time when all of the switch parts are in stable equilibrium, as shown in Fig. 1, the displacer is at once lowered to the position in which it is shown in Pig. 3, the inside and outside mercury levels rising together as the plunger displaces mercury until the opening 4l is closed, and thereafter gas is trapped within the thimble and placed under pressure due to the height of the outside column of mercury. The time delay element Il is selected so that the time required for the inside mercury level to rise from the heightindicated by the line I2 to the lowest edge 4I oi the cup 22, corresponds to the specified minimum operate time, as for example one second. It makes no difference whether the relay is re-energlzed immediately after the circuit through the switch has been opened or not for the mercury within the cup 22 is continually being lowered with respect to the mercury column that has risen in the thimble 33 (when in the position shown in Fig. 3) except for a brief interval of time during which the column of mercury rising on the outside of the cup 22 reaches `and rises above the level of mercury indicated by the line u within the cup 22, and since the time delay opening 3| produces a relatively long time delay as compared with the time delay element 34, the mercury column within the displacer il spills over the edge 42 of the cup 22 and closes the circuit through the switch before the merM cury in the cup 22 has a chance to re-establish contact with the pool of mercury 21 in the cup 26. In closing the circuit in this manner, the bridging of the contacts is first completed between the contact 2l and the exposed portion 9 of the lead I6, and as soon as the cup 22 has filled, the electrical path of least resistance is between the contacts 2l and 29. The electrode 9, therefore, serves the function of insuring that the electrical load is at no time required to pass through the time delay opening 3l with the consequent altering of the time delay characteristics of the element 2l due to the deleterious effect of overheating of the mercury in the opening 30. Since de-energization of the relay coil i substantially instantaneously restores the displacer 3| to the position in which it is shown in Fig. 1 with the outside mercury level and inside mercury level at the same height (the column of mercury within the cup 2l will. of course, be higher until the time delay element 2l has had full opportunity to function). energization of the coil il at any time subsequent to the breaking of the switch contacts, is certain to reproduce the condition described with respect to Fig. 3 and produce the specified minimum operate time when the coil I is recycled through the switch contacts, which may be accomplished in conventional manner by connecting the coil in series with the contacts, as shown in Figs. l and 4. After the relay coll l0 has been energized, subsequent de-energization of the coil i I will produce the specified quick release reset regardless of the extent to which the mercury level is permitted to rise by continued energization of the coil. In other words, it does not matter whether the relay coil Ill is energized when the mercury level within the displacer Il has reached the point I3 to close the contacts, or whether it has been energized for a longer period to bring the mercury level to its position of equilibrium, indicated at I5, with the outside mercury level. In either case. de-energization of the coil I I causes the displacer Il to rise by itsl buoyancy to the position shown in Fig. l for the displacer will carry up with it a column of mercury within the thimble until the opening 40 rises above the outside mercury level. As soon as this happens, gas enters the thimble 33 through the opening 40, thereby by-passing the time delay element 34 and causing the mercury that is carried up in the thimble to fall into the cup 22 illling it to its maximum level (this action being illustrated in Fig. 2). The

time delay element, 30 then functions to time the movement of mercury from its maximum level at 43 to the level at which it breaks the electrical circuit through the switch contacts.

Since the de-energization of the coil -ill can do no more than illl the cup 22. the switch has the operating characteristic of quick release reset.

Back contact switch (Figs. 4 and 5) The back contact switch shown in Figs. 4 and 5 has the following operating characteristics: Normally closed contact (i. e. a back contact switch), minimum release time, and quick operate reset.

The relay comprises an operating coil 50 having a magnetic circuit which includes pole pieces 5I and 52 which receive the switch generally indicated at 53. The switch comprises an enve-v lope 54 through the base of which lead-ins 55 and 56 are pinch-sealed. The lead-ins project upwardly within the envelope and the former is insulated for a portion of its length from the main body of mercury fill 51 by an insulating sleeve 58 which is enlarged as at 59 to form a seat for a time delay cup, generally indicated at 60, which is similar in all respects to the cup 29 of the front contact switch shown in Figs. 1-3 inclusive, and therefore requires no further description.

The lead-ins 55 and 56 extend upwardly into the cup 60, the latter electrode being at all times in contact with the body of mercury 6I in the cup 60 and the former contact being insulated from the mercury body 6| by an insulating sleeve 62 that is enlarged at 63 to form a seat for a smaller cup 64 in which a pool of mercury 65 is at all times retained in contact with the exposed end 66 of the lead-in 55. The cup 60 is provided with a mercury leakage opening 61 of appropriate size to suit the prescribed operating conditions of the relay.

'I'he mercury level Within the envelope is manipulated by means of a displacer, generally indicated at 68, which occupies the position shown in Fig. 4 when the relay coil 50 is deenergized. At this positionl it will be noted 0 that the circuit through the lead-ins 55 and 56 is closed.

'I'he displacer 68 comprises a glass thimble 69 which is closed at its upper end by a time delay element 10 which, in this instance, is in the form of a ceramic tube 1I. It is fused, or otherwise bonded to 'the marginal walls of an opening 12 provided in the top wall of the thimble 69 with a glass bead 13 being applied to the upper end of the tube to restrict the passage of gas into and out of the displacer (whenever the time delay element is supposed to function) to that portion of the tube 1I which projects above the walls 12 of the opening.

An iron sleeve 14 is telescoped over the thimble 69 and held in place by upper and lower cushioning springs 15 and 16, respectively, which frictionally engage the projecting ends of the thimble 69. Guide washers 11 are provided as before to guide the movement of the displacer within the envelope.

Operation of back contact switch When the coil 50 is de-energized, and all parts of the switch are in stable equilibrium, the switch parts are in the position shown in Fig. 4, with the circuit through the leads 55 and 56 closed. If the coil 50 is now energized, the displacer rises to the position shown in Fig. 5, but in doing so carries up with it a quantity of mercury within the thimble 69 that is released to flood the cup 60 as soon as the lower end of the thimble 69 rises above the outside mercury level. At this instant, gas freely enters the thimble 69 through the bottom 18 of the thimble and the mercury that is being carried upwardly within the thimble is immediately released into the cup 60. The time that is required for the mercury level to,v fall from its maximum level in the cup 60 (in-` dicated by the line 19) to the level at which the body 60 of mercury separates from the pool 65 of mercury within the cup 64 is determined solely by the rate of iiow of mercury through the opening 61 of the cup' 60 and when this opening is properly selected as to size, the desired operate time may be obtained.

Since the rising of the displacer always carries a suilicient quantity of mercury upwardly to fill the cup 60 (even though the relay coil is energized immediately after the circuit through the electrodes 55 and 56 have been closed) the switch possesses the desired operating characteristic of quick operate reset.

When the. relay coil 50 is de-energized to drop the displacer 68 to the position shown in Fig. 4, gas is entrapped within the thimble 69 as soon as the displacer strikes the mercury illl 51 and as a result, the mercury level on the outside of the displacer may rise to a position such as indicated by the line 80 while the inside mercury level (i. e. the level of the mercury column within the thimble 69 but outside of the cup 60) may be lowered to a position such as indicated by the line 8l. switch, the time delay element 10 is considerably quicker in its action than the time delay element 61 and as a result, the mercury column within the thimble 69 and outside of the cup 60 rises at a given rate until the mercury column overflows the top of the cup 60 thereby closing the circuit through the switch. The time required for this action to take place is dependent upon the characteristics of the time delay element 1I,`

but it is obvious that this element may be chosen to provide the required minimum release time.

The relationship between the time delay characteristics of the opening 61 and the gas leakage wall 1I insures that the relay has minimum release time for the same reason that the corresponding relationship of the two time delay elements of the relay shown in Figs. 1-3 insures minimum operate time.

In both front and back contact forms of the invention, it is unnecessary to have the gas leakage time delay element on the displacer selected with relatively short time delay characteristics as compared with the mercury leakage opening in the mercury, or in cases where the relay coil is recycled through the switch contacts. In other words, when the operation of the relay coil is controlled by the switch contacts, it is possible to have the long time delay in the displacer element 84 and the short time delay in the iixed element 2l, in which case, the only diii'erence in switch operation would be that when the displacer was lowered by energiaation oi the coil ID, the time delay element Il would control the making o! the contacts not by causing mercury to spill over the top of the cup 22, but by controlling the rate ol the mercury iiow into the opening 3l. A corresponding action would take place with the back contact switch shown in Figs. 4 and 5.

What I claim is:

l. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury till, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement oi mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, one oi said time delay elements comprising a gas leakage device associated with the displacer, and the other comprising a nxed mercury cup provided with a restricted wall opening for the timed passage of mercury, said one electrode projecting into said cup.

2. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury iill, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one ot said electrodes to delay the movement of mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, one of said time delay elements comprising a gas leakage device and the other comprising a ilxed mercury cup provided with a restricted wall opening for the timed passage of mercury, said one electrode projecting into said cup.

3. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury ll, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement ci mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, one ci said time delay elements comprising a gas leakage device associated with the displacer, and the other comprising a mercury cup provided with a restricted wall opening for the timed passage of mercury, said one electrode projecting into said cup, and said displacer being telescoped over the mercury cup whereby upward movement of the displacer carries with it a column of mercury within the displacer, and means for releasing the column oi mercury to till the cup.

4. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury illl, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associatedwith one oi said electrodes to delay the movement oi' mercury with relation to said electrode upon a change in the condition ot the electrical circuit through the coil, one of said time delay elements comprising a gas leakage device associated with the displacer, and the other comprising a mercury cup provided with a restricted wall opening ior the timed passage of mercury, said one electrode projecting into said cup, and said displacer being telescoped over the mercury cup whereby upward movement of the displacer carries with it a column of mercury within the displacer, and means Ior releasing the column of mercury to iill the cup, the time delay element associated with the displacer being relatively fast in its action as compared Y to the time delay element associated with the cup whereby the relay is characterized by having a minimum release time even under abnormal recycling conditions.

5. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury illl, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement ci mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, one of said time delay elements comprising a gas leakage device associated with the displacer, and the other comprising a mercury cup provided with a restricted wall opening for the timed passage of mercury, said one electrode projecting into said cup, and said displacer being telescoped over the mercury cup whereby upward movement of the displacer carries with it a. column of mercury within the displacer, and means for releasing the column oi' mercury to till the cup, the time delay element associated with the displacer being relatively tast in its action as compared to the time delay element associated with the cup whereby the relay is characterized by having a minimum operate time even under abnormal recycling conditions.

6. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil. said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one oi said electrodes to delay the movement of mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, one of said time delay elements comprising a gas leakage device associated with the displacer, and the other comprising a mercury cup provided with a restricted wall opening for the timed passage of mercury, said one electrode projecting into said cup, and said displacer being telescoped over the mercury cup whereby upward movement ol the displacer carries with it a column o! mercury within the displacer, and means lor releasing the column of mercury to fill the cup, said means being arranged so that the cup is completely iilled with mercury lor each upward stroke ofthe displacer to provide quick reset for the switch un-` der all abnormal or normal recycling conditions when the relay coil is recycled through the switch electrodes.

7. In a mercury switch relay having prescribed operating characteristics, the combination oi' a relay coil, a switch associated with the coil, said vswitch comprising a switch envelope, spaced of the electrical circuitf through the coil, one of All fin

said time delay elements comprising a gas leakage device, and the other comprising a mercury cup provided with a restricted wall opening for the timed passage of mercury, said one electrode projecting into said cup, and the said displacer being telescoped over the mercury cup whereby upward movement of the displacer carries with it a column of mercury within the displacer, and means for releasing the column of mercury to fill the cup, said relay being characterized by having minimum release time under abnormal recycling conditions when recycling of the relay coil is controlled by the switch electrodes.

8. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury ll, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement of mercury with relation to said electrode upc a change in the condition of the electrical circuit through the coil, one of said time delay elements comprising a gas leakage device, and the other comr sing a mercury cup provided with a restricted wall o` ming for the timed passage of mercury, said one electrode projecting into said cup, and the said displacer being telescoped over the mercury cup whereby upward movement of the displacer carries with it a column of mercury within the displacer, and means for releasing the column of mercury to fill the cup, said relay being characterized by having minimum operate time under abnormal recycling conditions when the recycling oi the relay coil is controlled by the switch electrodes.

9. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury iill, a hollow displacer responsive to the coil for shifting the mercury level, and means including a time delay element associated with one of said electrodes to delay the movement of mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, said time delay element comprising a mercury cup provided with a restricted wall opening for the timed passage of mercury, said one electrode projecting into said cupand said displacer being telescoped over the mercury cup and having means associated therewith whereby upward movement of the displacer carries with it a quantity of mercury, and means ior releasing said quantity of mercury to ll the cup, said displacer, mercury cup and mercury carrying means associated with the displacer being so arranged that the cup is completely filled with mercury for each upward stroke of the displacer to provide quick reset for the switch under all abnormal or normal recycling conditions when the relay coil is recycled through the switch electrodes.

10. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury iill. a hollow displacer responsive to the coil for shitting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement of mercury with relation to said electrode upon a change in the condition o'f the electrical circuit through the coil, and means for mounting said time delay elements in the switch in such cooperative relation that when the relay is recycled through the switch electrodes, the switch is characterized by a slow make, slow break of the circuit through the electrodes, and is further characterized by having a quick reset at least for one direction of movement of the mercury.

l1. In a mercury switch relay having prescribed operating characteristics, the combination oi a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement of mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, one of said time delay elements comprising a gas leakage device associated with the displacer and the other comprising a relatively fixed timing device associated with said one electrode, and means including at least one of said devices for causing the switch to be characterized by having quick reset at least for one direction of` movement of the mercury when the relay is recycled through the switch electrodes.

12. In a mercury switch relay having a predetermined minimum release time, the combination of a relay coil, a switch of the slow make, slow break type associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow displacer responsive to the coil for shifting the mercury level, a time delay element carried by the displacer constructed and arranged so that downward movement of the displacer in the mercury fill causes the mercury to slowly rise in the displacer at a rate proportionate to the action of the time delay element, while upward movement of the displacer causes the mercury to move quickly in a direction that tends to empty the displacer of mercury, and a second time delay element including portions rigidly telescoped over one of the electrodes and arranged with respect to the displacer and other switch elements so that for normal recycling time, the normal operate and release times are obtained, but for sub-normal release recycling time, the predetermined minimum release time is effected.

13. In a mercury switch relay having a predetermined minimum release time, the combination of a relay coil, a switch of the slow make, slow break type associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow displacer responsive to the coil for shifting the mercury level, a time delay element carried by the displacer constructed and arranged so that downward movement of the displacer in the mercury iill causes the mercury to slowly rise in the displacer at a rate proportionate to the action of the time delay element, while upward movement of the displacer causes the mercury to move quickly in a direction that tends to empty the displacer oi' mercury, and a second time delay element including portions rigidly telescoped over one o! the electrodes and arranged with respect to the displacer and other switch elements so that when the relay is recycled through the switch contacts, the predetermined minimum release me is always affected.

14. In a mercury switch relay having prescribed operating characteristics, the combination ot a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow displacer responsive to the coil for shitting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement oi' mercury with relation to said electrode upon a change in the cmdition of the electrical circuit through the coil, and means for mounting said time delay elements in the switch whereby prescribed operate time conditions are obtained essentially through the operation of one oi.' said time delay elements, and certain prescribed release time conditions are obtained essentially through the operation of the other time delay element.

15. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope. spaced electrodes in the envelope, a mercury illl, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement oi' mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, and means i'or mounting said time delay elements in the switch whereby prescribed operate time conditions are obtained essentially through the operation of one oi' said time delay elements, and certain prescribed release time conditions are obtained essentially through the operation of the other time delay element, the time delay element controlling the operate time conditions being fast in its action as compared to the time delay element controlling the release time conditions.

16. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury illl, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement of mercury with relation to said electrode upon a change in the condition oi! the electrical circuit through the coil, and means for mounting said time delay elements in the switch whereby prescribed operate time conditions are obtained essentially through the operation of one of said time delay elements, and certain prescribed release time conditions are obtained essentially through the operation o! the other time delay element, the time delay element controlling the release time conditions being fast in its action as compared to the time delay element controlling the operate time conditions.

17. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury iill, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one oi said electrodes to delay the movement of mercury with rclation to said electrode upon a change in the condition of the electrical circuit through the coil, and means for mounting said time delay elements in the switch whereby prescribed operate time conditions are obtained essentially through the operation of one cf said time delay elements, and certain prescribed release time conditions are obtained essentially through the operation oi' the other time delay element, one of said time delay elements being associated with said displacer and being fast in its action as compared to the other ot said time delay elements.

18. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury lill,

a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one oi' said electrodes to delay the movement of mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, and means for mounting said time delay elements 1n the switch whereby the switch is characterized by quick reset at least for one direction of movement of the mercury.

19. In a mercury switch relay having prescribed operating characteristics, the combination oi' a relay coil, a switch associated with the coil, said switch comprising an envelope, spaced electrodes in the envelope, a mercury illl, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one oi' said electrodes to delay the movement ci mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, one oi said time delay elements comprising a gas leakage device telescoped over one of said electrodes and arranged to control the movement of mercury toward said electrode and the other one of said time delay elements comprising a mercury cup provided with a restricted wall opening for the timed passage oi.' mercury, arranged to control the movement of mercury away from said electrode, whereby the switch is characterized by a delayed make and a delayed break of the circuit through the electrodes.

20. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising an envelope, spaced electrodes in the envelope, a mercury illl, a hollow displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement of mercury with relation to said electrode upon a change in the condition of the electrical circuit through the coil, one of said time delay elements comprising a gas leakage device telescoped over one of said electrodes and arranged to control the movement of mercury in one direction with respect to said electrode and the other one of said time delay elements comprising a mercury cup provided with a restricted wall opening for the timed passage of mercury, arranged to control the movement oi.' mercury in the other direction with respect to said electrode, whereby the switch is characterized by a delayed make and a delayed break of the circuit through the electrodes.

CARL H. LARSON. 

